A bolt 1 called caulking bolt includes a protrusion 3 on a seat surface which is a lower surface of a bolt head part 2 as shown in FIG. 1, and also includes a screwless part or small-diameter part 6 provided at the upper end of a male part 5 formed in a shaft part 4. When this bolt 1 is driven into a metal plate 7 as shown in FIG. 2, the metal plastically flows into the outer periphery of the protrusion 3 and the screwless part or small-diameter part 6, so that the bolt 1 is caulked and fixed to the metal plate 7. Thereafter, the bolt can be used to attach other members, as with stud bolts.
Such a bolt is set in a prepared hole formed in the metal plate 7 by a human hand or robot hand, and then caulked by a caulking device provided with a punch. However, when the number of the bolts used is increased, there is demanded a technique of supplying the bolts into a progressive mold to perform supply and caulking as a single operation, not such two-stage operation.
The device which performs supply and caulking as a single operation in such a manner has already been put in practical use for caulking nuts. The details of the device are as taught by JP H8-90360 A of the present applicant, and a caulking nut is supplied in a horizontal posture (posture where the axis is perpendicular) by air pressure from the lateral direction relative to a caulking device, and driven into a metal plate below by a punch lowering from above.
A bolt, however, is vertically long unlike a flat nut, and thus cannot be supplied in a posture where the axis is perpendicular similarly as in JP H8-90360 A. Since a vertically-long bolt must be driven into a metal plate in a state where the bolt is kept vertical to the metal plate, the posture of the bolt cannot be easily held as compared with that of the nut. Also for these reasons, any caulking technique that ensures supply and caulking as a single operation has not been put in practical use so far.